Low-color stiff pvb laminates

Abstract

The present invention describes laminate articles comprising a stiff, low-color PVB sheet having a YID of less than 12 and having a low concentration of plasticizer in the PVB composition, wherein the sheet is prepared from a composition that includes a PVB bleaching compound. A sheet of the present invention is useful for making glass laminates useful for parts in making cars, boats, trains, buildings, display cases, and other articles that utilize transparent glass laminates.

1 . A plasticized PVB composition consisting essentially of: polyvinylbutyral (PVB) having a hydroxyl number of from about 15 to about 25; a plasticizer or mixture of plasticizers present in a finite amount of less than about 30 pph based on the dry weight of the resin composition; a surfactant; and optionally including either (i) a PVB bleaching compound, or (ii) an antioxidant and a UV light stabilizer, or (iii) both (i) and (ii).  
     
     
         2 . The composition of  claim 1  wherein the plasticizer is 3GO.  
     
     
         3 . The composition of  claim 2  wherein the plasticizer is dibutyl sebacate.  
     
     
         4 . The composition of  claim 3  wherein the composition includes a bleaching compound, an antioxidant, and a UV light stabilizer.  
     
     
         5 . The composition of  claim 4  wherein the bleaching compound and the surfactant are the same compound.  
     
     
         6 . The composition of  claim 5  wherein the surfactant is DOSS.  
     
     
         7 . The composition of  claim 6  wherein the antioxidant is 2,2′-methylenebis(6-t-butyl-4-methylphenol).  
     
     
         8 . The composition of  claim 7  wherein the plasticizer is present in an amount of from about 5 to about 30 pph.  
     
     
         9 . The composition of  claim 8  wherein the plasticizer is present in an amount of from about 15 to about 30 pph.  
     
     
         10 . The composition of  claim 9  wherein the plasticizer is present in an amount of from about 18 to about 28 pph.  
     
     
         11 . The composition of  claim 10  wherein the plasticizer is present in an amount of from about 18 to about 22 pph.  
     
     
         12 . An article comprising at least one layer of the PVB composition of  claim 1 .  
     
     
         13 . The article of  claim 12  wherein the interlayer has a yellowness index (YID) of less than about 12 and wherein the interlayer was obtained by a process comprising the step: extrusion of PVB sheet at a temperature in the range of from about 225° C. to about 245° C.  
     
     
         14 . The article of  claim 13  wherein the article is a laminate comprising at least one layer of PVB and at least one layer of glass wherein the PVB layer has a thickness in the range of from about 0.254 mm to about 1.6 mm.  
     
     
         15 . The article of  claim 14  wherein the laminate comprises more than one PVB interlayer, and wherein the combined thickness of the PVB interlayers is in the range of from about 0.75 to about 1.6 mm.  
     
     
         16 . The article of  claim 14  wherein the laminate is useful as: architectural glass; automobile glass; train glass; or boat glass.  
     
     
         17 . The article of  claim 16  wherein the laminate is useful in an automobile, train, or boat as a: windshield; light cover; body glass, such as sun roof, moon roof, or back and/or side window; internal door; cabinet; cabinet door; partition, and the like.  
     
     
         18 . The article of  claim 17  wherein the article is an automobile windshield, light cover, moon roof, sun roof, or back and/or side window.  
     
     
         19 . The article of  claim 18  wherein the laminate is useful for: external windows on buildings; external doors; partitions; office windows; office doors; glass partitions; table tops: shelves; cabinet doors; protective covers for tables; room dividers; picture frame glass; display cabinets; display cases, and the like.  
     
     
         20 . The article of  claim 12  wherein the laminate is obtained by a process comprising the steps: (i) bringing a PVB polymer interlayer and a glass plate into contact; (ii) removing air from between the glass and the interlayer; and (iii) applying heat and external pressure to adhesively bond the glass plate to the interlayer.  
     
     
         21 . A process for preparing a low color PVB sheet comprising the steps: (I) admixing polyvinyl alcohol, butyraldehyde, an acid or mixture of acids, water, and a surfactant (II) stabilizing the mixture obtained in step (I) by (a) raising the pH of the mixture to at least pH 10 (b) isolating the resin by draining the liquid, (c) washing the resin with neutral pH water; (III) plasticizing the PVB resin composition with from about 30 to about 50 pph of plasticizer based on the dry weight of the PVB resin; (IV) optionally mixing (a) a PVB bleaching compound and/or (b) an antioxidant and a UV light stabilizer with the PVB resin composition; and (V) extruding the PVB composition at a temperature of from about 225° 0  C. to about 245° C. to obtain a PVB sheet having a Tg in the range of from about 35° C. to about 60° C., and a YID of less than about 12.